Previous research has shown that 3-methylindole, (3MI), a ruminal metabolite of tryptophan, can cause acute pulmonary edema and emphysema in cattle, sheep, and goats. Three-methylindole is rapidly metabolized and both hydroxylated and oxindole derivatives of 3MI are excreted in the urine. Investigations will be conducted on the uptake, concentration, and localization of 3MI in the lung and these results will be correlated with electron microscopic evaluation of early lung damage. We will use in vitro and in vivo studies to evaluate the metabolism of 3MI by the lung. The metabolism of 3MI by lung and liver tissue through the mixed function oxidase system and pyrrolooxygenases will be investigated. We will attempt to determine whether toxic metabolic intermediates such as epoxides are formed and result in lung damage. Experiments with laboratory animals in which 3MI is administered by inhalation and other routes are in progress. In addition, research will be continued on the characteristics of the 3MI producing organism and a method to prevent the formation of 3MI in the rumen of cattle under natural conditions. BIBLIOGRAPHIC REFERENCES: Dickinson, E. O., Yokoyama, M. T., Carlson, J. R., and Bradley, B. J. Induction of pulmonary edema and emphysema in goats by intraruminal administration of 3-methylindole. Am. J. Vet. Res. 37, 667-672, 1976. Terry, M. L., Bradley, B. J., Hammond, A. C., Cummins, K. A., Carlson, J. R., and Dickinson, E. O. 3-Methylindole and naturally occurring ABPE. J. Animal Sci. 42, 1575, 1976 (# 93).